U.S. patent number 7,347,225 [Application Number 10/493,351] was granted by the patent office on 2008-03-25 for highly flexible multistructure tube.
Invention is credited to Philippe Nobileau.
United States Patent |
7,347,225 |
Nobileau |
March 25, 2008 |
Highly flexible multistructure tube
Abstract
A multi-structure pipe intended to transport a fluid, used in
particular in oil production, including a first hollow and closed
tubular structure having a set of substantially circumferential
slits, each slit extending on an arc of more than 180.degree. and
defining a tension band extending with a helix shape along the said
first tubular structure, and at least a second tubular structure
having also at least a tension band also in helix shape of the same
direction and pitch as the first tubular structure, and the tension
bands of the first and second tubular structure being maintained at
a fix distance from one another by support of the second tension
band on the first tubular structure to provide the tension capacity
of the pipe.
Inventors: |
Nobileau; Philippe
(Villefranche sur Mer, FR) |
Family
ID: |
8868863 |
Appl.
No.: |
10/493,351 |
Filed: |
October 23, 2002 |
PCT
Filed: |
October 23, 2002 |
PCT No.: |
PCT/FR02/03642 |
371(c)(1),(2),(4) Date: |
September 29, 2004 |
PCT
Pub. No.: |
WO03/036151 |
PCT
Pub. Date: |
May 01, 2003 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20050087248 A1 |
Apr 28, 2005 |
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Foreign Application Priority Data
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Oct 24, 2001 [FR] |
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01 14002 |
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Current U.S.
Class: |
138/114; 138/119;
138/130 |
Current CPC
Class: |
F16L
11/121 (20130101); F16L 11/14 (20130101) |
Current International
Class: |
F16L
11/00 (20060101) |
Field of
Search: |
;138/131,121,119,114,115,139,130,143,DIG.5 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Hook; James
Claims
The invention claimed is:
1. Multi-structure pipe of great flexibility (1, 10 or 20) intended
to transport a fluid, including an assembly of at least two
structures concentric to the axis of the pipe and means to contain
the transported fluid, wherein said assembly of structures includes
a first internal tubular structure (3, 12 or 22) having a set of
substantially circumferential low pitch helical slits (5) bordering
hoop resistant bands, each said slit extending on an arc of more
than 180 degrees and less than 360 degrees in order to define a
continuous opposite high pitch first tension load band (7, 11 or
21), and at least a second structure (13-15 or 23) having at least
one other tension load band (6, 13 or 23) with a helix of same
direction and pitch as said first tension load band (7, 11 or 21),
and said other tension load bands (7-6, 11-13 or 21-23) of said
structures are maintained to a fix distance from said first tension
load band by support on the outside of said first internal tubular
structure (3, 12 or 22) to provide the capacity in tension of the
pipe.
2. Multi-structure pipe (1, 10 or 20) according to claim 1 wherein
said means to contain the transported fluid (4, 18 or 24) are
located inside one of said structures.
3. Multi-structure pipe (1, 10 or 20) according to claim 1 wherein
the means of containing the transported fluid, comprise a sealed
pipe (4, 14 or 24).
4. Multi-structure pipe (10 or 20) according to claim 3 wherein the
pipe (14 or 24) includes a cylindrical conduit having corrugations
(17) to improve its flexibility.
5. Multi-structure pipe (20) according to claim 4 wherein
reinforcing helix shape wires (25) are located inside the helix
groove formed by said corrugations.
6. Multi-structure pipe (1 or 10) according to claim 3 wherein the
sealed pipe is located on the outside of the first tubular
structure (2, 12 or 22).
7. Multi-structure pipe (20) according to claim 3 wherein the
sealed pipe is placed inside the first tubular structure (22).
8. Multi-structure pipe (10) according to claim 1 wherein the means
of containing the transported fluid, comprise a band, with
corrugation lengths substantially equal to the slit length (5),
welded on its two edges to said tension load band (11) of the first
tubular structure.
9. Multi-structure pipe (1) according to claim 1 wherein said
second structure is a tubular structure having a second set of
substantially circumferential low pitch helical slits (5) bordering
second set of hoop resistant bands, each said slits extending on an
arc of more than 180 and less than 360 degrees in order to define a
continuous opposite high pitch second tension load band (7, 11 Or
21).
10. Multi-structure pipe (10) according to claim 1 wherein said
second structure (13-15) comprises a winded wire (15) with small
pitch and opposite direction to the tension band (13).
11. Multi-structure pipe according to claim 1 wherein said first
tubular structure is fabricated by helix welding of a metal strip
comprising slits of length smaller than the width of said strip and
substantially perpendicular to the direction of said strip.
12. Multi-structure pipe according to claim 1 wherein said slits do
not go through the structure and are formed by stamping material,
providing a sealed tubular structure.
Description
TECHNICAL FIELD
This invention relates to large diameter flexible pipes of for
drilling and oil production, which are able to withstand high
pressure while maintaining great flexibility.
STATE OF THE ART
In oil field production, flexible pipes are used in various
applications such as the pipeline. A flexible pipe is herein
defined as a pipe which during its transport and its installation
is sufficiently flexible along its longitudinal axis to accept a
minimum radius of curvature of at least 10 times smaller than that
of the rigid tube of the same dimensions. These flexible pipes must
be able to withstand high internal pressures that can reach 5,000
to 10,000 psi (35 MPa to 70 MPa). In underwater production
utilisation, they must support collapse due to external pressures
as well as tension loads during their installation.
Patent EP 871,831 describes a monolithic flexible device comprising
a single metallic tubular structure associated to sealed means
containing the transported fluid through this tubular structure.
The tubular structure is comprised of at least two sets of slits
extending along the wall to provide flexibility. Each slit extend
in a substantially circumferential direction on an arc smaller than
180.degree.. The space between the set of slits defines at least
two tension bands that extend along the tubular structure of the
pipe. The set of slits and the bands extend along helix. The arches
generated by the slits are also on helixes, but in the opposite
direction with a greater helix angle with regard to the axis of the
flexible pipe.
The monolithic flexible pipes gain in simplicity compared to the
other flexible devices of large diameter available based on the
cable technique but the presence of the two bands of tension
diametrically opposed on the same monolithic tubular structure
generates important plastic deformations in the small pitch arches
which links the tension bands in particular when reeled and
unreeled for transportation and installation This is due to the
small length of these arches, which from the design of the
monolithic flexible device cannot exceed a half circumference. Use
of this flexible pipe is thus limited to few cycles of
reeling/unreeling and must thus be kept to applications known as
static where there are none or few alternatives bending in service.
The piping interconnexion between oil production components on the
seafloor illustrates a static or quasi-static example of flexible
pipes where the flexible capability of the pipe is needed only to
facilitate its transport, its installation and connections on the
seafloor.
Nevertheless, there are needs in particular in riser and the links
between the seafloor and the surface where a flexible pipe must be
able to support alternate flexion during service that can exceed 15
years. It is thus desirable to improve the monolithic tubular
structure described in the patent EP 871,831 to give it acceptable
fatigue performances when subject to alternative flexing.
SUMMARY OF THE INVENTION
The object of the invention is to provide a pipe for the fluid
transport with a flexibility in the elastic range of the
component's material that is greatly improved in order to be able
to support alternative flexing while subject to high pressures.
The object of the invention is thus a multi-structure pipe intended
to transport a fluid, used, in particular in oil production,
including an assembly of tubular structures concentric to the pipe
axis and means to contain the transported fluid, the assembly of
tubular structures including a first hollow and closed structure
having a set of substantially circumferential slits, each slit
extending on an arc of more than 180.degree. and defining a tension
band extending with a helix shape along the first tubular
structure, and at least a second tubular structure having also at
least a tension band also with a helix shape of same direction and
same pitch that the tension band of the first tubular structure,
and the tension bands of the first and second tubular structure are
maintained to a fix distance from one another by support between
the second tension band on the first tubular structure to provide
the capacity in tension of the pipe.
According to a first embodiment of the invention, the flexible pipe
is comprised of two concentric tubular structures with slits and
the means to contain the transported fluid is a sealed envelope
located between the two tubular structures. This sealed envelope
can be a metal pipe with a corrugated wall located between the two
tubular structures with slits.
According to a second embodiment, the external structure is a
tension band, which could be comprised, of several wires on which a
low pitch winded tubular structure provides a burst resistance of
the flexible pipe.
Last of all according to a third embodiment, the external structure
is only a tension band and the means to contain the fluid is
located inside the first internal tubular structure. The means to
seal is obtained by a thin metal pipe corrugated in helix which can
be reinforced for higher external pressure by a carcass of
reinforcing profiled wire inserted inside the inside helix groove
formed by the corrugations.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a perspective view illustrating a flexible portion of
pipe constructed in accordance to a first embodiment of the
invention.
FIG. 2 is a sectional view of the flexible pipe of FIG. 1.
FIG. 3 is a perspective view of a flexible pipe according to a
second embodiment of the invention.
FIG. 4 is a sectional view of a flexible pipe according to a third
embodiment of the invention.
FIG. 5 is a perspective view illustrating a flexible pipe shown in
a sectional view on FIG. 4
DETAILED DESCRIPTION OF THE INVENTION
While referring to FIG. 1, the flexible pipe 1A has a first
internal tubular structure 3 made from a monolithic metal pipe. The
tubular structure 3 is cylindrical and comprises a set of parallel
slits 5. Each slit 5 has a circumferential length defined by a
first end 5a and another opposed end 5b. The length extends
substantially more than 180.degree. and preferably between
200.degree. and 300.degree.. The set of slits 5 defines a band 7
that is solid with no slit 5. This band 7 forms a helix with high
pitch and small angle of about 10 to 30.degree.. The width of the
band 7 is uniform and constant along the central portion of the
tubular structure 3. The width of the band 7 extends out on 25 to
45% of the circumference whereas the width of the set of slits 5
covers the remaining portion of the circumference. Arches 9
delimited by slits 5 are preferably on parallel helixes with
opposite direction of the helix of band 7. The helix pitch of the
arches is low with an angle preferably ranging between 70 and
85.degree..
In the illustrated embodiment, a sealed envelope 4 surrounds the
internal tubular structure 3. This envelope 4 can be made by
continuous extrusion of a polymer pipe. An external tubular
structure 2 made also from of a monolithic metal tube surrounds the
sealed envelope 4. The tubular structure 3 is cylindrical and also
comprises a set of parallel slits 5. Each arch 8 also has a
circumferential length defined by a first end 8a and another
opposed end 8b. The length extends also substantially more than
180.degree. and preferably between 200.degree. and 300.degree.. The
ends of arches 8 are linked by a tension band 6 that is solid and
has no slits 5. This band 6 forms a high pitch helix parallel and
of same angle that band 7. As band 7, the width of the band 6 is
uniform and constant along the tubular structure 2. The width of
the band 7 also covers 25 to 45% of the circumference whereas the
width of the set of slits 5 covers the portion of remaining
circumference. This width can be different to the width of the
tubular structure 3 but preferably the band 6 section measured on a
transversal section to the tubular structure 2 must be
substantially equal to the band 7 section measured on a transversal
section to the tubular structure 3.
One thus obtains a flexible pipe 1 able to withstand compression or
tension loads along its longitudinal axis 1' by interaction of the
tension bands 6 and 7 between themselves. Indeed, on FIG. 2 one
notes that the tension bands 7 and 6 that have parallel helix are
diametrically opposed in order to compensate for the imbalance
induced in first tubular structure 3 by the offset of tension band
7. When the flexible pipe 1 is subjected to a tension, this
interaction is carried out by contact through the sealed envelope 4
of the interior face 6a of the tension band 6 of the external
tubular structure 2 on the arches 9 of the internal tubular
structure 3 which are connected to the tension band of tension 7 of
the internal tubular structure 3. When the tube is subjected to
compression, it is then the outside 7b of the tension band 7 that
enters in contact with the arches 8, through the sealed envelope 4,
which are connected to the tension band 7 of the internal tubular
structure 3. One notes as well as the tension bands 6 and 7 are
free to move from one another longitudinally, which gives its
flexibility to pipe 1 but are able to maintain a radial interaction
in order to avoid a crushing of the tubular structure under simple
tension or the buckling of this one when the flexible pipe is
subjected to compression. Due to the location of the sealed
envelope 4 between the two tubular structures 2 and 3, this
envelope is supported on arches 8 when it is subjected to a fluid
internal pressure and is supported on arches 9 when it is subjected
to a fluid external pressure.
On FIG. 3, a second embodiment of the invention is shown. This
embodiment is preferred in the case the flexible pipe, according to
the invention, will be subjected to very high tension as in the
case of flexodrilling drill string. The flexible pipe 10 includes a
first tubular structure 12 that comprises a tension band 11 and
arches 17 of opposed direction helixes with high and small pitch as
for the tubular structure 3. The originality comes from the fact
that the tension band 11 is thick in order to be able to support a
strong tension although it is of a small diameter. As in the first
embodiment, one finds a sealed envelope 14 that is preferably of
metal impermeable to fluid and features a corrugated wall 18.
Corrugations 18 are preferably on helixes with multiple starts. The
external tubular structure is substantially different from the one
on the first embodiment of the invention, due to the fact that it
does not comprise a monolithic tubular structure. In fact, this one
comprises one or more metal wires 13 a, b, c having a total section
13 which will be balanced with section 11 of the tension band of
internal tubular structure 12 as it has been previously explained.
This tension band 13 is combined with a rectangular wire winding 15
wrapping the tubular structure with the same helix direction that
arches 17 of the internal tubular structure 12. These wires 15 can
be either metal or high performance reinforcing fibbers (glass,
aramid, carbon) in a hollow metal envelope. These wires can be
connected between themselves and possibly to the tension band 13 at
the location 16.
Thus, one obtains a tubular structure with high performance easy to
produce, on continuous line, by winding and welding the edges of a
sealing band 14 with a very high pitch on the internal tubular
structure 12, then winding the tension band(s) 13 with the same
high pitch with the same direction as the tension band 11 followed
at last by the winding of the wire mesh 15 resistant in hoop with
small pitch and in the opposite direction of the tension band 11.
Since the configuration of the sealed envelope 14 again between the
two tubular structures 12 and 13-15, this envelope is supported by
the winding of wire 15 when subjected to a fluid internal pressure
and is supported on the arches 17 of the internal tubular structure
12 when subjected to a fluid external pressure.
FIGS. 4 and 5 illustrate a third embodiment of the invention, which
will be preferred for, cost saving reasons when external pressure
or compression services are low. Nevertheless, one finds the first
monolithic tubular structure 22 with its single tension band 21 and
its arches 27. On the other hand, the sealed envelope, preferably
out of corrugated thin pipe 24 is laid out inside the first tubular
structure 22. This makes it possible to use arches 27 to resist the
external pressure and to avoid having to wind another structural
mesh to take care of this as per the two preceding embodiments. It
is now necessary to have only one or more tension band(s) 23 to
balance the flexible pipe. To avoid lateral displacement of the
tension band 23 when sliding, stops 28 are located on arches 27 of
the first tubular structure. An outer jacket 29 is installed to
isolate the tubular structure from the external environment.
To improve the resistance in external pressure of the corrugated
thin metal envelope 24, a reinforcing helix shaped wire 25 can be
inserted inside the helix fold formed by the corrugations.
The invention offers significant improvements for the tubular
structure of flexible pipes. The first tubular structure is
monolithic but is comprised only of a single tens ion band in order
to give maximum flexibility to the arches, which closes the tubular
structure around this tension band. This tubular structure, being
unbalanced from the radial offset of the single tension band, is
rebalanced by the winding of one or more wires with the same pitch
and same direction as the tension band of the monolithic tubular
structure making contact with the arches directly or indirectly of
the monolithic tubular structure to be able to withstand
substantial tension loads.
It is also possible to seal the first tubular structure by
vulcanising an elastomer in the slits. In this case the slits can
have a no rectilinear form to increase the surface of contact and
thus the width of shearing of the elastomer.
One can also form the first tubular structure by welding in spiral
a thick band comprising slits of which the length is smaller than
the width of the band laid out substantially perpendicular to the
direction of the band. In this case it is advantageous to carry out
the sealing by welding on the two edges, a corrugated thin sheet
band having corrugation on a length smaller than the width of the
band covering the slits area, on the thick band.
Finally one can conceive to carry out the first tubular structure
by welding in spiral a single band on which corrugation folds have
been formed by stamping directly the thick band and pushing the
material along lines substantially perpendicular to the direction
of the band but without going through the band.
Whereas this invention was illustrated by the three embodiments, it
will appear to the man skilled in the art that it is not thus
limited, but is likely to accept variations within the extent of
the protection conferred by the claims.
* * * * *